Devices that evaluate gait motion using various kinds of sensor devices have been developed for the purpose of observing the course of a disease, preventing falls, and the like. In medical practice, a subject is required to do an action (standing on one foot or the like) needing balance ability, and the subject's behavior is observed to determine a fall risk.
However, in the related art, measurement and estimation of a disease degree are performed under the assumption that the subject keeps walking, and so it is difficult to estimate a walking condition and a fall risk in a short time from a start of walking. In addition, the technique executed in the medical practice has a problem in that the subject has a risk and feels pressured since the subject is required to do an action needing balance ability.